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PVC May Increase Lead Leaching

Ayear-long study from the Civil and Environmental Engineering Department of
Virginia Tech suggests that polyvinyl chloride plastic pipes may create
an environment for lead contamination.

IAPMO
recently reported in its I-Connection publication that a year-long study from the Civil and
Environmental Engineering Department of Virginia Tech suggests that polyvinyl
chloride (PVC) plastic pipes may create an environment for lead contamination.

The
study found that chloramine, a chemical added by most public water systems to
kill bacteria, can cause a chain reaction: the chloramine decays and forms
ammonia, which in turn supports "autotrophic microbial
nitrification." The nitrification process stimulates growth of
heterotrophic bacteria (which grew easily in PVC pipe, but not in copper),
which lowers the pH levels. Water with low pH (acidity), causes the corrosion
of the brass fixtures and pipefitting common in plumbing systems.

Update: PPFA Responds

The Plastics Pipes and Fittings Association in the US has responded to a Plastics & Rubber Weekly (PRW.com)
article, titled “Plastic pipes may indirectly pose ‘lead problem’,” published on
4 June, which referred to the above study published in the peer-reviewed Environmental
Science & Technology.

In a letter, Dick Church, executive director of the PPFA, wrote:

“Plastic plumbing pipe contains no lead. Therefore, your recent story on
“Plastic pipes may indirectly pose lead problem,” is a huge leap from any
reality since it appears to blame lead extraction on the use of plastic pipe. In
effect, the referenced experiment, partially funded by the Copper Development
Association, created an artificial water world where water without disinfectant
was used to farm bacteria in pipes by deliberately fertilizing the water with
ammonium sulfate. In short and at best, the experiment does not represent
real-world conditions. Its most dramatic shortcoming is its failure to recreate
what actually happens in plumbing systems that are treated with chlorine,
chloramines or may be disinfected in other ways.

“Another significant shortcoming of the experiment is its insufficient
duration. Its conclusions are based on the absence of a bio-film on the copper
after 200 days. A bio-film had formed on the plastic, lead and brass by that
point, but not on the copper. According to Lehtola et al*, bio-film formation is
a normal process common to all piping systems and equalizes just past 200 days.
Since the copper itself is toxic to aquatic life, including the bacteria studied
by this experiment, the water in the experiment’s copper systems maintains a
higher (less acidic) pH than the water in plastic (CPVC), lead and brass
systems. Hence, the bacteria enhancing nitrification had free reign in the test
– in a normal plumbing system using chorine or chloramines, the bacteria would
not develop, or, at least, would be kept in check. There’s no reason to believe
water pH would normally change dramatically in the real-world as it apparently
did in the experiment. The water pH is more likely to be highly variable due to
the source of the water than the impact of the bacteria under any conditions.

“We hope everyone will keep in mind that the best way to avoid lead
contamination in plumbing systems is to use products that do not contain lead.
Blaming non-lead containing products for lead contamination just won’t cut it."

* Microbiology, chemistry and biofilm development in a pilot drinking water
distribution system with copper and plastic pipes, Water Research 38 (2004)
3769-3779.

Events

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Products

Revised to include details on the latest technologies, Valve Handbook, Third Edition, discusses design, performance, selection, operation, and application. This updated resource features a new chapter on the green technology currently employed by the valve industry, as well as an overview of the major environmental global standards that process plants are expected to meet.

Check out November 2018 issue of Plumbing & Mechanical , featuring our Cargo Vans model year 2019, a vehicle build for your business, a few guidelines to installing a tankless water heater , and much more.